Speed control mechanism



April 3, 1945. A. ARMENTROUT SPEED CONTROL MECHANISM Fiied Nov. 11, 1942 2 sheets-sheet 1 April 3, l945 A. L. ARMENTRoU-r 2,372,702

SPEED CONTROL ME CHANI SM Filed Nov. 1l, 1942 2 Sheets-Sheet 2 :HTIHH Il Hllllllllllll!" //7 ren/ar r//iz/l l; rm enf/"aaf- Patented Apr. 3, 1945 UNITED STATES PATENT OFFICE- SPEED CONTROL MECHANISM Arthur L. Armentrout, Long Beach, Calif.

Application November 11, 1942, Serial No. 465,225

(Cl. 'I4- 293) y6 Claims.

eration of the driven unit where the speed of operation of the driving unit is variable. In many instances a driving unit which has a variable speed of operation is employed to operate a driven unit intended for uniform speed operation. For

example, thisis the situation where an internal combustion engine is employed to drive an electric generator. The drive mechanism of the present invention when employed in such situations is operable to maintain constant speed operation of the driven unit even though the speed of operation of the driving unit may vary'considerably.

Another object of this inventionI is to provide a drive yor transmission of the character referred to that is automatic, being operable to automatically maintain a substantially constant speed of operation of the drivenl unit.

Another object of this invention is to provide a constant `speed drive of the character referred to that may be readily regulated to provide for any required differential in the speed of operation of the driving and driven units and to maintain substantially uniform operation of the driven unit at the selected speed. The differential in the speeds of operation of the driving unit and driven unit may be regulated at will and the driven unit will be operated at the selected rate even though the driving unit has a variable speed.

Another object of this invention is to provide a simple, practical drive or transmission that is operable to maintain a substantially constant speed of operation of a driven unit whose speed tends to vary. In many cases a drive unit having a substantially uniform speed of operation is employed to drive a driven unit sucli as a machine tool, or the like, whose speed is variable. The mechanism of the present invention when employed in such a combination serves to maintain a substantially constant speed of operation of the driven unit. Y

`Another object of this invention is to provide a drive of the character referred to inv the preceding paragraph that may be easily manually regulated to vary the differential in the speeds of operation of the two units as conditions of operation of the driven unit may require.

A further object of this invention is to provide a drive of the character referred to that is small, compact and self-contained and` readily installed between the drive and driven units.

The various objects and features of my invention will be fully understood from the following detailed description of typical preferred forms and applications of the invention, throughout which description reference is made to the accompanying drawings, in which:

Fig, 1 is a side elevation of one form of the invention as used in conjunction with a variable speed drive unit and a constant speed driven l unit. Fig. 2 is a side view of the drive associated with a constant speed drive unit and a variableV speed driven unit. Fig. 3 is an enlarged vertical detailed sectional view of the differential gear means of the invention showing the associated fluid brake in elevation. Fig. 4 is an enlarged fragmentary side elevation illustrating the regulating means of the apparatus shown in Fig. 1. Fig. 5 is an enlarged view partly in section, illustrating the valve for controlling the fluid brake. Fig. 6 is a view similar to Fig. 1 illustrating another form of the invention, and Fig. 7 is a view similar to Fig. 6 illustrating still another form of the invention.

The drive of the present invention has numerous applications and may be varied to adapt it to given uses or installations. In the drawings I have shown two typical forms and applications of the invention, it being understood that these are merely illustrative and are not to be construed as limiting or restricting either the scope or the application of the invention.

In Fig. 1 of the drawings the drive is shown interposed between a variable speed prime mover or driving unit A in the form of an internal combustion engine, or the like, and a driven unit B in the form of an electric generator. In Fig. 2 of the drawings the drive serves to connect a constant speed drive unit C such as an electric motor and a variable speed driven unit D which may be a machine tool or any other device whose speed of operation tends to vary. Certain elements are common to the several illustrated forms of the invention and where corresponding parts appear in the several figures corresponding reference numerals are employed to designate them.

The invention as illustrated in Figs. 1, 3, 4 and 5 of the drawings may be said to comprise, generally, a differential gear unit IIl interposed between the drive unit A and the driven unit B, a fluid brake II associated with the differential unit I and a control I2 for the brake.

In the simple arrangement illustrated the shaft I3 of the drive unit A is longitudinally aligned with the driven shaft I@ and the differential gear unit I0 is connected between the two shafts. I have shown a speed change gear unit I5 associated with the driven unit B and the driven shaft It extends from the speed change gearing toward the drive unit A. The differential gear unit Il comprises opposing gears I xed or lgeyed on the opposing ends of the drive and drivenshafts i3 and III. In practice the gears I S may have a substantial diameter and the gears are provided at their peripheries with opposed bevelled teeth lll.

The differential gear unit Iii includes a rotatable support or spider mounted to turn about the common axis of the shafts I3 and II. In practice this rotatable support may be in the form of a housing or casing I8 enclosing the gears I6. I have shown bearings IQ on the opposite sides of the casing I8 riding on the shafts i3 and ill to support the casing for free rotation. Aligned shafts or trunnions 2@ are mounted on the casing I8 and projects into its interior. Pinions ZI are rotatable on the trunnions Eil with the casing I8 and mesh with the teeth Il of the two opposing gears It. The engagement of the gears I6 with the gears 2i causes independent rotation of the casing IB unless the casing is held against such movement. If this rotation of the casing I3 is unhindered no rotation is transmitted to the driven shaft Ill. On the other hand, if the casing I8 is positively held against rotation the meshing gears I6 and 2l provide a positive drive between the drive and driven shafts I3 and I 4l.

The fluid brake II is operable to control rotation of the casing IB and thus control or govern the speed ratio of the drive between the shafts I3 and Ill. The fluid brake comprises a suitable positive displacement pump arranged to be driven by the rotatable casing IS. In practice the pump of the brake means I I may be a simple gear pump 22 arranged with its shaft 23 in parallel relation with the shaft It. A pinion 2li is provided on the pump shaft 23 and meshes with a ring gear 25 on the casing I8. The ring gear 25 may be formed on the periphery of a plate 2d which closes an end of the casing I8. I prefer to provide the pinion 2d with an overrunning clutch Q so that the pump shaft 23 is rotated only when the drive is serving to rotate the driven shaft Ill in the forward direction. The pump 22 may be supported in any appropriate manner.

The pump 22 is provided with a by-pass or circulation line 2l extending from its high pressure outlet toits low pressure inlet. It Will be seen that the pump 22 serves to circulate fluid through the line 2l. When the line 21 is fully open the pump 22 offers little or no resistance to rotation of the casing I8. On the other hand, if the flow through the circulation line 2l is restricted the pump 22 operates as a brake to resist rotation of the casing I8 and by slowing down the casing It effects a change in the speed ratio of the shafts I3 and I, increasing the speed of rotation of the driven shaft lli. A reservoir R communicates with the low pressure side of the line l. Valve means is interposed in the circulation line 2l so that the braking action of the pump 22 may be controlled to govern the differential gear means I@ and thus vary the speed at which the driven aevavoa shaft Ill is rotated. The valve 28 for controlling the circulation line 2l is preferably a balanced valve and may be provided with a projecting operating stern 29 (see Fig- 5). It will be seen that upon operation or movement of the valve stem 2li the braking effect of the brake II is varied and accordingly the speed of rotation of the driven shaft Il is changed,

The control I2 operates to automatically control the valve 23 and thus control the brake means II and the differential gear means I0. The control I2 is governed by the speed of rotation of the driven shaft Ill, In the embodiment of the invention illustrated the control I2 includes a diaphragm means 3U for operating the valve 28. The Stem 2E of the valve 2B may be directly operated by the diaphragm of the means 3S. The Idiaphragm means 30 is operated by a pump means which in turn is driven by the driven shaft Iii. A gear 3l is provided on the driven shaft I4 and meshes with a pinion 32 which is fixed on the shaft of a pump 33. The gear 3| is provided with-an overrunning clutch 8 and is rotated only when the driven shaft It rotates in the forward direction. A line 3ft extends from the high pressure side of the pump 33 to the fluid pressure side of the diaphragm means 30. Where the parts are related as illustrated the fluid pressure supplied to the diaphragm means 3U tends to open the valve 28. A spring 39 associated with the valve stem Z9 yieldingly urges the valve 28 to the closed position. A bleed line or by-pass line 35 communicates with the pressure line SII and extends to the low pressure side of the pump 33 and a liquid reservoir 38 communicates with the low pressure side of the line 35. The by-pass line 35 is under the control of a suitable manual valve The valve 36 may be in the nature of a needle valve capable ofaccurate adjustment or regulation. Regulation of the valve 36 varies the rate of bleeding or by-passing of the fluid from the pressure line Eil of the diaphragm means SII. By regulating` the setting of the valve 36 the diaphragm means 3U maybe made to control the brake means I I to provide for any selected differential in the speed of rotation between the drive shaft It and the driven shaft Il at any given or required speed of rotation of the driven shaft III. As the pump 33 merely serves to circulate ud through the by-pass 35 and to develop a sufficient pressure for the operation of the diaphragmmeans 3@ it need not be a large pump.

It may be preferred to provide a reversing means for the drive, such reversing means being particularly advantageous in marine drives. The reversing means provided by the invention lncludes a clutch for connecting the housing I8 with the drive shaft I3 so that the casing is positively driven by the drive shaft. With the casing I8 clutched with the drive shaft I3 the pinions 2i which mesh with the two gears I6 are locked against turning on their individual axes and this locks the two gears Iii so that they turn as a unit. This provides a positive drive between the shafts I3 and lli in a direction which is the reverse of the direction of the normal drive through the free dierential gear unit i8. The clutch means for connecting the casing I8 with the drive shaft I3 may include a clutch part Ill formed or mounted on the casing IB. A clutch member I2 is splined or slidably keyed on the drive shaft I3 and is adapted to cooperate with the clutch part di for the transmissionof rotation to the casing Ill. A shift lever lil is pivoted between its ends and has a yoke cooperating with the clutch member 42 to move the member between the engaged and the released positions.

The overrunning clutches 8 and 9 do not transmit rotation when the casing I8 is clutched with the drive shaft I3. Thus the fluid brake II and the control I2 are disconnected or idle when the drive is reversed. It is to be observed that when the drive is reversed there is a positive driving connection between the drive shaft I3 and the driven shaft I4. To restore the drive to its normal condition to provide for the rotation of the shaft I4 in the forward direction the lever 43 is operated to disengage the clutch member 42 from the part 4I.

In the operation of the mechanism illustrated in Figs. 1, 3, 4 and 5 of the drawings the valve 38 may be set or adjusted to provide for the normal or required speed of operation of the driven shaft I4 and the driven unit B. With the drive unit A operating at its normal or intended speed there is no change in the system. However, if the speed of operation of the drive unit A changes, due to an increased or decreased load on the primary driven element or unit (not shown) the drive means of the invention goes into operation to maintain a substantially constant speed of operation of the driven unit B. Thus in the event that the speed of the drive unit A increases the speed of the driven shaft I4 tends to increase correspondingly. An increase in the speed of rotation of the driven shaft I4 of course produces accelerated operation of the pump 33 and increased pressure is applied to the diaphragm means 30. Such increased pressure in the diaphragm means 30 tends to open the valve 28 providing for a greater volume of flow through the line 2l with a corresponding reduction in the braking action of the means II. The resultant increase in the speed of rotation of the casing I8 causes the driven shaft I4 to be rotated at a slower rate. Thus, the increase in the speed of operation of the drive unit II is automatically compensated for.

In the event the speed of operation of the drive unit A is reduced the driven shaft I4 tends to turn at a slower rate. Accordingly, the pump 33 driven from the shaft I4 develops less pressure and reduced pressure at the .diaphragm means 30 results in outward movement of the valve stem 29 and a decreased ow through the circulation line 21. The braking action of the brake means II is increased and the casing I8 is made to turn slower, thus bringing about a change in the differential drive and an increase in the speed of rotation of the driven shaft I4. This compensates for the reduction in the speed of operation of the drive unit A. The compensating drive or constant speed drive is entirely automatic in its operation but may be regulated by simple operation of the valve 36 to regulate the differential between the drive and driven shafts. When it is desired to reverse the drive the lever 43 is operated to engage the clutch member 42 with the part 4I. This provides for a direct reverse drive between the shafts I3 and I4, as described above.

In Fig. 2 of the drawings the drive of the invention is interposed between a drive unit C having a constant speed and a driven unit D whose speed of operation may vary due to operating conditions. In this application of the invention the drive includes the differential gear unit I connected between the drive shaft I3a and the driven shaft I4a. The driven shaft I4 drives the unit D through a suitable speed change gear unit |53. The differential gear unit III may be the same as in the preceding form of the invention and the fluid brake means II may be the same as above described. invention the valve 28 in the circulation line 21 may be hand operated. It will be seen that by appropriate manual operation of the valve 28 a greater or lesser braking action may be obtained to obtain the desired differential in the .speed of rotation of the drive.` shaft I3a and driven shaft |43. It is to be understood that the control I2 described above may be employed when the drive is utilized as illustrated in Fig. 2. Where the control I2 is embodied in the drive it is operatively connected with the driven shaft I4a through the gearing 3I-32 as above described. With the control means I2 incorporated in the drive the mechanism serves to maintain the substantially constant speed of rotation of lthe driven shaft I4a even though the driven unit D tends to vary in its rate of operation.

Fig. 6 illustrates the drive of the invention embodying another form of control IZa. The differential gear unit Ill and the brake II may be the same as described above and the drive may embody the above described reversing means and reservoirs. I have shown the drive serving to connect the drive shaft I3 and the driven shaft I4. In this form of the invention 'the control means I2a includes an electromagnetic means or solenoid coil 50 for operating the valve 28 of the brake II. The electromagnetic means 50 is such that it may open the valve 28 varying extends against the action of thespring 39. The energizing circuit for the electromagnetic means 50 includes leads 5I and 52 extending from its terminals to a generator 53. The generator 53 is driven by the shaft I4. The gear 3I on the shaft I4 meshes with a gear 32a fixed on the shaft of the generator 53. The gear 3I is connected with the shaft through the medium of an overrunning clutch 8 solthat it is rotated only when the shaft rotates in the forward direction.

It will be seen that the speed of operation of the generator 53 is determined by the speed of rotation of the shaft I Il and that the action of the coil 50 is governed by the current supplied by the generator. When the speed of rotation of the shaft I4 is reduced less current is delivered to the coil 50 and the vvalve 28 moves toward its closed position restricting the flow of fluid through the line 2l thus increasing the braking action so that the speed of rotation of the shaft I4 is increased. When the speed of rotation of the drive shaft I4 increases above the normal speed the output of the generator 53 is increased and the coil 5D moves the valve 28 toward the open position permitting a greater flow of fluid through the circulating line 2l. This reduces the braking action provided by the brake II and the speed of rotation of the shaft I4 is reduced.

A variable rheostat 55 may be connected in the lead 5I and may be operated to vary the differential in the speeds of rotation of the drive shaft I3 and driven shaft I4. It will-be apparent how the rheostat 55 serves the same function as the valve 36 in the form of the invention illustrated in Figs. 1, 3, 4 and 6.

In Fig. '7 of the drawings I have illustrated the differential gear unit I0 interposed between the shafts I3 and I4 as above described. In this embodiment of the invention vthe rotation of the casing I8 of the differential gear unit I0 is controlled by an electric brake 60. The shaft of the electric brake 60 is provided with a gear il for In this form of the wanted change in its speed of rotation.

4 asvaroe meshing with the gear on the casing IB. The gear El is equipped with an overrunning clutch Sb which transmits rotation to the brake shaft only when the shaft I is being rotated in the forward direction. The electric brake Si! is of the well known type whose braking action is proportional to the current supplied to it.

Theoperating and controlling circuit for the electric brake 6I) includes leads 52 and 63 extending to an appropriate source of electrical energy (not shown). The brake 60 when normally or fully energized from this source may operate to positively hold the casing It against turning.

The energizing circuit for the brake 60 is under the control of a means responsive to the speed of rotation of the driven shaft I4. This means includes the gear 3l connected with the driven shaft lli by the overrunning clutch 8 as described above. A suitable generator 54 is provided adjacent the gear 3l. A pinion 65 is fixed on the shaft of the generator 65 and meshes with the gear 3i. Leads GS extend from the terminals of the generator fili to an electromagnetic means or solenoid coil 6l. A rheostat 68 is interposed in the brake energizing lead 62 and is under the control of the solenoid coil el. The parts are related so that the setting of the rheostaty ls governed by the output of the generator S4.

With the drive of Fig. 7 conditioned for the forward drive of the driven shaft I4, the brake 663 and its control operate to maintain a substantially constant speed of rotation of the driven shaft'. In the event that the speed of rotation of the driven shaft I@ increases the output of the generator 64 increases and the solenoid coil Si changes the setting of the rheostat 6B. This reduces the current being delivered to the brake E59 with the result that the casing I8 is allowed to rotate at an increased speed. An increase in the speed of rotation of the casing I8 is accompanied by a decrease in the speed of rotation of the driven shaft Il and the increased speed of the driven shaft is automatically compensated for. In the event that the driven shaft I4 rotates at, a reduced rate of speed the output of the generator B4 is correspondingly reduced and the setting of the rheostat 6B is changed so that more current is supplied to the brake 60. The brake offers increased resistance to rotation of the casing I8 so that the speed of rotation of the driven shaft Ill is increased to compensate for the un- The reversing means and the overrunning clutches t and 9b operate as described above.

Having described only typical preferred forms and applications of my invention, I do not wish to be limited or restricted to the specific details herein set forth, but wish to reserve to myself any variations or modifications that may appear to those skilled in the art or fall within the scope of the following claims.

Having described my invention, I claim:

l. A drive for connecting a drive shaft and a driven shaft including differential drive means interposed between said shafts and including a rotatable part whose speed of rotation determines the ratio of the speeds of rotation of the shafts, a fluid brake for governing rotation of said part, a control valve for the brake, and fluid pressure operated means responsive to the rotation of the driven shaft for controlling said valve, and including a pump driven from the driven shaft, a

diaphragm for operating the valve, a pressure line connecting the pump and diaphragm, and a bypass for regulating the pressure developed by the pump.

'2. A drive for connecting a drive shaft and a driven shaft including differential drive means interposed between said ,shafts and including a rotatable part whose speed of rotation determines the ratio of the speeds of rotation of the shafts, a fluid brake for governing rotation of said part, a control valve for the brake, fluid pressure responsive means for operating said valve, and means operated by the driven shaft generating fluid pressure for operating the last named means including a pump driven by the driven shaft and a fluid circuit from the pump to the pressure responsive means including a by-pass.

3. A drive for connecting a constant speed shaft and a variable speed shaft including differ ential drive means operatively connecting the shafts and including a rotatable part whose speed of rotation governs the ratio of rotation of the shaft, brake means for controlling the rotation of said part, means responsive to the speed of rotation of the driven shaft for automatically varying the action of the brake means including a pump, a. fluid pressure actuated control for the brake means, and a fluid circuit connecting the pump and the control and including a by-pass, and manual means for controlling the by-pass.

4. A drive between a variable speed drive shaft and a constant speed driven shaft comprising a differential gear drive between the shafts including a part whose speed of rotation determines the speed ratio of the drive, a fluid brake for controlling the rotation of said part, a valve for governing said brake, fluid pressure responsive means for operating the valve, pump means driven by the driven shaft for supplying fluid pressure to the pressure responsive means, and controllable by-pass means for the pump means for varying the pressure supplied to the pressure responsive means.

5. A drive between a variable speed drive shaft and a constant speed driven shaft comprising a differential gear drive between the shafts including a part whose speed of rotation determines the speed ratio of the drive, a fluid brake for controlling the rotation of said part, a valve for governing said brake, fluid pressure responsive means for operating the valve, a pump driven by the driven shaft for supplying fluid pressure to the pressure responsive means, a by-pass for connecting the intake and discharge sides of the pump, and a valve in said by-pass operable to govern the pressure supplied to the pressure responsive means.

6. A drive for connecting a constant speed shaft and a variable speed shaft including differential drive means operatively connecting the shafts and including a rotatable part whose speed of rotation governs the ratio of rotation of the shafts, brake means for controlling the rotation of said part including a pump driven by said part, a line connecting the intake and the discharge of the pump, a valve in said line, diaphragm means for operating the valve, a pump operated by one of said shafts for supplying uid pressure to the diaphragm means, a by-pass connecting the intake and discharge ports of the pump, and a valve for controlling said by-pass.

ARTHUR L. ARMENTROUT, 

